Device for controlling injection quantity of fuel for internal combustion engines

ABSTRACT

A device for controlling injection quantity of fuel for internal combustion engines, in which the injection quantity of fuel is controlled by transmitting lift of a solid cam to a control rack through a roller lever having a roller lever return spring, wherein said roller lever return spring is in the form of a torsion spring and is mounted on a rotating shaft of said roller lever, and includes a rack return spring adapted to usually urge said control rack in the direction of increasing fuel.

United States Patent Nishizawa et a1.

DEVICE FOR CONTROLLING INJECTION QUANTITY OF FUEL FOR INTERNAL COMBUSTION ENGINES Inventors: Kazuro Nishizawa; Yoshiaki Ohtsuka, both of l-ligashi-Matsuyama; Hideo Fukushima, Saitama; Hiroshi Otsuka, Higashi-Matsuyama, all of Japan Assignees: Diesel Kiki Kabushiki Kaisha,

Tokyo; Toyo Kogyo Co., Ltd., both of Hiroshima, Japan Filed: Feb. 5, 1974 Appl. No.: 439,723

Foreign Application Priority Data Feb. 15, 1973 Japan 48-19164[U] U.S. CL. 123/140 R; 123/140 CC;

123/140 MC Int. Cl. F02D 1/04 Field of Search... 123/140 R, 140 MC, 140 CC References Cited UNITED STATES PATENTS 9/1955 Links 123/140 R Oct. 28, 1975 2,818,053 12/1957 Shallenberg 123/140 R 3,358,664 12/1967 Thompson 123/140 R 3,426,739 2/1969 Bailey 123/140 R 3,601,108 8/1971 Nambu 123/140 R 3,747,580 7/1973 Savage t 123/140 R 3,771,917 11/1973 Davies 123/140 R Primary E.\'aminer-Char1es .1. Myhre Assistant Examiner-Daniel J. OConnor Attorney, Agent, or Fi rmI-Ienry R. Lerner [57] ABSTRACT A device for controlling injection quantity of fuel for internal combustion engines, in which the injection quantity of fuel is controlled by transmitting lift of a solid cam to a control rack through a roller lever having a roller lever return spring, wherein said roller lever return spring is in the form of a torsion spring and is mounted on a rotating shaft of said roller lever, and includes a rack return spring adapted to usually urge said control rack in the direction of increasing fuel.

1 Claim, 6 Drawing Figures US. Patent Oct.28, 1975 Sheet 1 of3 3,915,139

PRIOR ART US. Patent 0a. 28, 1975 Sheet 2 of3 3,915,139

US. Patent Oct. 28, 1975 Sheet3of3 3,915,139

DEVICE FOR CONTROLLING INJECTION QUANTITY OF FUEL FOR'INTERNAL COMBUSTION ENGINES The present invention relates to a device for controlling injection quantity of fuel for internal combustion engines.

It is known in a gasoline engine that due to a limit to a range in an ignitable rate of air to fuel, the rate of change in supplied quantity of fuel relative to a rotational speed is different between the case in which a throttle valve is choked (low load) and the case in which the throttle valve is used (high load). For that reason, in the gasoline engine incorporating a fuel injection device therein, a solid cam displaced in a rotational direction by variation of load (opening of the throttle valve) and in an axial direction by the centrifugal force of a flyweight in relation to the rotational speed of the engine is used so that a fuel controlling lever on the fuel injection pump is operated through a lever member having a follower in contact with the cam surface by means of a spring.

An object of the present invention is to provide a device for controlling injection quantity of fuel for internal'combustion engines, which, by simple reconstructions, eliminates the unstabilized condition of the controllability irrespective of operation of the compensation mechanism and is designed so that the control force is not varied so much even if the cam lift increases, providing the great effect in practical use.

Now the foregoing object and advantages of the present invention are secured, together with others which will occur to those skilled in the art, will be more apparent from the following description making reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a conventional device for controlling injection quantity of fuel, in accordance with the prior art,

FIG. 2 is a perspective view of a device for controlling injection quantity of fuel according to the present invention,

FIG. 3 is a graphic view showing the relation between the pressing force of a roller relative to a solid cam by a roller lever return spring and a rack return spring, and the cam lift according to the prior art conventional device,

FIG. 4 is a graphic view similar to FIG. 3 according to the present invention,

FIG. 5,is a graphic view showing the relation between the force pressing the roller against the solid cam by the roller lever return spring and the cam lift, and

FIG. 6 is a longitudinal vertical cross section illustrating an example mounting the rack return spring in the device according to the present invention.

A basic construction of the conventional device for controlling injection quantity of fuel in accordance with the prior art will now be described.

Referring now to FIG. 1 showing the conventional device, in accordance with the prior art there is shown a cam shaft 1 which is rotated in proportion to a rotational speed of an engine. A flyweight 2 is mounted on the cam shaft 1 and overcomes a controller spring 3 to open as the cam shaft 1 rotates so that this flyweight causes a solid cam 4 slidably mounted on the cam shaft 1 to move in the axial direction by the proportionate amount to the rotational speed of the engine. An idling adjusting screw may adjust the starting action of the controller spring 3 to adjust the number of idling revolutions. In the outer periphery of the solid cam 4 there is provided a cam profile (fuel is increased with decrease of cam lift) suited for rotation of the engine and further provided a pin 7 to be engaged with a swing lever 6 adapted to rotate the solid cam 4 on the cam shaft 1. The swing lever 6 connected with an accelerator pedal (not shown) causes the solid cam 4 to rotate in relation to the opening of a throttle valve as the accelerator pedal is displaced. A roller 10 rotatably mounted on' a roller lever 9 having, as its intermediate fulcrum, a pin 8 on the body of the device, is urged against the solid cam 4 by means of a roller lever return spring 11 interposed between the end opposite thereto and the body. At the end where the roller lever return spring 11 on the roller lever 9 is provided, there is mounted a pinl3 through an arm 12, this pin 13 slidably engaging with a slot 16a made at one end of a connecting levei" 1'6 rotatably mounted about a shaft 15 on the temperature and atmospheric pressure compensation portion' 14 as an intermediate fulcrum, and a pin '19 on a guide angle 18 having a control rack (fuel controlling leve'r) 17 is slidably engaged with a slot 16b at the other endof the lever 16. The guide angle 18 is provided with a'rack position adjusting screw 20, and the rotation of the screw 20 varies the position of the control rack 17 with respect to the guide angle 18. Further, the guide angle 18 is provided with a flange portion 21 having a groove 22 cut therein, with which a pin 23 on the body of the device is engaged to allow the control rack to move' in the axial direction but to prevent rotation thereof. Between the guide angle 18 and the body of the device there is provided a rack return spring 24 to urge the control rack 17 in the fuel decreasing direction and to prevent clearances between the control rack 17 and the connecting lever 16, and between the connecting lever 16 and the roller lever 9.

With this arrangement, operation will be described.

Referring to FIG. 1, when the accelerator pedal (not shown) is depressed, the throttle valve opens and the swing lever 6 moves upwards and the solid cam'4 rotates til it reaches the position corresponding to the opening of the throttle valve. With this, the roller 10 changes the position of the injection quantity of fuel along the profile of the cam, and the roller lever return spring 11 pulls the roller lever 9 to rotate it about the pin 8 in the clockwise direction. The pin 13 on the arm 12 rotates the connecting lever 16 in the clockwise direction about the pin 15 on the compensation portion 14, and the pin 19 in engagement with the slot 16b in the connecting lever 16 moves the guide angle 18 leftwards against the rack return spring 24. Consequently, the control rack 17 is moved to the position corresponding to theopening of the throttle valve to thus increase fuel. When the number of revolutions is increased at this position of the solid cam 4, the flyweight 2 opens overcoming the controller spring 3 to cause the solid cam 4 to move rightwards. At this time, the roller 10 is moved upward due to the profile of the solid cam 4 and the roller lever 9 is rotated in the counterclockwise direction overcoming the roller lever return spring 1 l. The connecting lever 16 is also rotated in the counterclockwise direction about the pin 15 and the guide angle 18, that is, the control rack 17 is moved in the fuel decreasing direction by the amount corresponding to the upward movement of the roller 10 to control the fuel to the quantity required for the rotational speed.

According to the above-described conventional device for controlling the injection quantity of fuel, as shown in FIG. 3 illustrating an ordinate which represents a force F by which the roller is pressed against the solid cam 4 and an abscissa which represents a cam lift L, a force El by which the roller 10 is pressed against the solid cam 4 by means of the roller lever return spring 11 and a force F2 by which the roller 10 is pressed against the solid cam 4 by means of the rack return spring 24 are reversely directed from each other, and it is consequently understood that the forces of the roller lever return spring 11 and the rack return spring 24 are determined in such a manner that the roller 10 is lightly pressed against the solid cam 4 by means of a resultant force of said two springs.

In the above-described construction, when a cooling water temperature is lowered to actuate the compensation mechanism, the fulcrum of the connecting lever 16 moves upward and the distance between the shaft and pin 19 is spaced greater than the distance prior to the compensation to increase the force F2 of the rack return spring 24, and a force as at F2 in FIG. 3, which serves to float the roller 10, is increased so as to hardly press the roller 10 against the solid cam 4, and particularly at the time of less cam lift, the roller 10 is floated, thus losing control.

For that reason, it may be considered that the roller lever return spring 11 be strengthened, but if such is made, a control force and operation of the compensation link mechanism may not be properly obtained and as shown in FIG. 4 illustrating an ordinate which represents the force F in which the roller 10 is pressed against the solid cam 4 by the roller lever return spring 11 and an abscissa which represents the cam lift L, a force a pressing the roller 10 against the solid cam 4 by the roller lever return spring 11 rapidly increases in proportion to the cam lift as the cam lift increases, and therefore even if the force of the roller lever return spring 11 is set so as to obtain a desired control force in a state of less cam lift, the force of the spring increases as the cam lift increases and the control force decreases.

In accordance with the present invention, therefore, in order to overcome the first disadvantage there is provided a return spring 24 acting in a fuel increasing direction in replacement of the rack return spring 24, shown in FIG. 2, so that a resultant force of F1 and F2 is positive at all times as shown in FIG. 5 similar to FIG. 3, and the roller 10 is never floated. In order to further overcome the second disadvantage, there is provided a roller lever return spring 11 in replacement of the roller lever return spring 11, on the fulcrum 8 of the roller lever 9, said spring ll"being in the form of a torsion spring, which is less in rate of increase of the force of a spring even if the quantity of displacement increases, so that the force of the roller lever return spring 11' and the force of the rack return spring 24' act in the direction where the roller 10 is pressed against the solid cam 4 as shown in FIG. 4 similar to FIG. 3, and as a result the force of the roller lever return spring 11' is made substantially constant as shown in b in FIG. 4. The reference character C designates a control limit of the pressing force by the spring. As shown in FIG. 6, the rack return spring 24' may be disposed between the flange 18' mounted on the end of the rack and the fuel injection pump housing 25.

Many variations may be effected without departing from the spirit of the invention. It is to be understood that, together with other variations in details, are anticipated by the appended claim.

What we claim is:

1. A device for controlling injection quantity of fuel for internal combustion engines, comprising,

a. a solid cam,

b. a roller lever mounted intermediate its opposite ends by a fulcrum pin,

0. a roller carried by said roller lever at one end thereof, and

d. a roller lever return spring comprising a torsion spring wound about said roller lever fulcrum pin and urging said roller against said cam whereby lift of said cam is transmitted to said roller and said roller lever, wherein there is provided a fuel control rack operatively connected to the other end of said roller lever whereby said cam lift is transmitted to said fuel control rack through said roller lever, and a rack return spring urging said fuel control rack in a direction of increasing fuel supply. 

1. A device for controlling injection quantity of fuel for internal combustion engines, comprising, a. a solid cam, b. a roller lever mounted intermediate its opposite ends by a fulcrum pin, c. a roller carried by said roller lever at one end thereof, and d. a roller lever return spring comprising a torsion spring wound about said roller lever fulcrum pin and urging said roller against said cam whereby lift of said cam is transmitted to said roller and said roller lever, wherein there is provided a fuel control rack operatively connected to the other end of said roller lever whereby said cam lift is transmitted to said fuel control rack through said roller lever, and a rack return spring urging said fuel control rack in a direction of increasing fuel supply. 